1. Field of the Invention
The present invention relates to a wafer holding plate used for wafer grinding apparatuses and a method for manufacturing the same.
2. State of the Art
Apparatuses for grinding the surface of a semiconductor wafer, such as a lapping machine or a polishing machine, are known in the prior art. A typical wafer grinding apparatus includes a table, which is fixed to a cooling jacket, and a wafer holding plate. The plate has a wafer adhering surface to which an adhesive, such as a thermoplastic wax, is applied. The adhesive attaches a semiconductor wafer to the plate.
Since the wafer adhering surface is flat, the adhesive must be relatively thick to ensure adhesion of the semiconductor wafer. It is difficult to apply the adhesive uniformly. As a result, parallelism between the wafer adhering surface and the semiconductor wafer is not achieved, which causes the semiconductor wafer to be held obliquely. Therefore, it is difficult to achieve highly accurate grinding.
Furthermore, if the surface of the plate is rough, the lands and pits of the plate surface are transferred to the rear surface of the wafer (the surface adhered to the plate) when the plate holding the wafer is pressed against a grinding surface. This decreases the accuracy and quality of the semiconductor wafer. Additionally, production efficiency decreases because wafers have to be reground to correct dimensions.